Good test-retest reproducibility for an instrument to capture self-reported melanoma risk factors.

OBJECTIVE: To examine the test-retest reliability and validity of self-reported items capturing phenotypic characteristics and sun exposure measures in the baseline survey instrument used for a prospective study of skin cancer and melanoma. STUDY DESIGN AND SETTING: Repeatability/validity study conducted among 114 participants randomly selected from the cohort to complete the survey instrument a second time and to undergo a physician skin examination. We calculated intraclass correlation coefficients (ICCs) and kappa (κ) statistics as measures of agreement for continuous and categorical measures, respectively. RESULTS: Measures of phenotypic characteristics showed moderate-to-high agreement (e.g., eye color, κ=0.87; 95% confidence interval [CI]: 0.80, 0.94). Measures of sun exposure had slightly lower estimates of agreement. The repeatability of items relating to medical and family history of skin cancer was high (e.g., the number of skin cancers removed surgically, κ(w)=0.79; 95% CI: 0.71, 0.88). Physician counts of nevi correlated well with categorical measures of self-reported nevus density at the age of 21 years but correlated only modestly with absolute nevus counts conducted by participants (ICC, 0.38; 95% CI: 0.19, 0.54). CONCLUSION: Our survey instrument demonstrated fair-to-good test-retest reliability for most self-reported risk factors for melanoma, indicating the suitability of these items for developing risk prediction tools in the future.

Cohort profile: the QSkin Sun and Health Study.

The QSkin Sun and Health Study comprises a cohort of 43 794 men and women aged 40-69 years randomly sampled from the population of Queensland, Australia in 2011. The cohort was established to study the development of skin cancer and melanoma in the population with the highest reported incidence of these diseases in the world. At baseline, besides demographic items and general medical history, information about standard pigmentary characteristics (including hair and eye colour, freckling tendency, tanning ability and propensity to sunburn), past and recent history of sun exposure and sunburns, sun protection behaviours, use of tanning beds and history of skin cancer was collected by self-completed questionnaire. Participants have given their consent for data linkage to the universal national health insurance scheme and for linkage to cancer registries and pathology databases, thus ensuring complete ascertainment of all future skin cancer and melanoma occurrences and medical treatments and other cancer events. Linkage to these registers will occur at predetermined intervals. Approval to access QSkin data can be obtained on application to the study investigators and submission of a formal research plan that has previous approval from the human research ethics committee of the applicant's institution.